The cooling module generally includes a heat generating body having one surface as a heat dissipating surface, a heat exchanger having one surface as a cooling surface opposite to the heat dissipating surface, an insulating plate interposed between the heat dissipating surface and the cooling surface and having an electrical insulation property and thermal conductivity, and heat dissipating grease.
Here, heat generated in the heat generating body is exchanged between the heat dissipating surface and the cooling surface through the insulating plate, and thereby is radiated to the heat exchanger. Further, in general, heat dissipating grease is interposed in a space between the cooling surface and the insulating plate and in a space between the heat dissipating surface and the insulating plate. Therefore, the cooling surface and the insulating plate are in close contact with each other, and the heat dissipating surface and the insulating plate are in close contact with each other, so that they are thermally connected to each other to be capable of performing the above-described heat exchange.
However, in this configuration, there is a possibility that the thermal resistance deteriorates since an abnormality such as a decrease of adhesion of the heat dissipating grease may occur due to the power cycle.
On the other hand, a joining between the cooling surface and the insulating plate and a joining between the heat dissipating surface and the insulating plate are made by a joining using Cu, Ag, etc. or a metallic joining such as brazing, and thereby a cooling module is provided with high thermal conductivity and insulation function (refer to Patent Literature 1).